It is well known that Infrared (IR) imaging technology has found many important application areas such as military, automobile heads-up-displays (HUD), medical diagnostics, surveillance for security, victim search for rescue teams, non-destructive testing for industrial applications, and geo-thermal event detection for environmental control. The devices used to generate the thermal map of the targets are passive devices that collect the optical signal radiated from the targets according to Planck's radiation law assuming that the targets behave as black bodies. According to the well known Planck's radiation law, the energy emitted per unit volume per unit wavelength from a blackbody (EA) is proportional to the temperature of the blackbody.
Therefore, it is possible to generate the thermal map of the target by detecting the radiated energy since the only parameters that determine the amount of energy are the temperature and the radiation wavelength. The interested spectrum of the radiation is classified as infrared (IR) band and IR band is further divided into bands as a function of wavelength as follows:                Near IR (NIR): 0.78-1 micron        Short wavelength IR (SWIR): 1-3 micron        Mid-wavelength IR (MWIR): 3-5 micron        Long-wavelength IR (LWIR): 8-14 micron        Very long-wavelength IR (VLWIR): 14-100 micron        
Each of these specific bands has their own properties, and specific detector technologies have been developed for these bands. For infrared imaging applications, MWIR and LWIR bands, where the transmittance of the atmosphere is high, are especially important. Transmittance through air is reduced by several factors as a result of scattering and absorption processes. The bands of operation should be selected specifically to each application. For instance, MWIR band is favorable if the target is relatively hot and the weather is clear, on the other hand LWIR band offers high sensitivity in hazy weather conditions.
Infrared imaging devices can basically be classified into two main groups according to the detection mechanism. Photon detectors deal directly with the interaction of the incoming photons with the electrons in the detector material. On the other hand, thermal detectors are the devices whose properties can be modulated by its temperature. Therefore, the detection mechanism of thermal detectors is indirect in the sense that the incoming radiation is first converted into heat energy and the generated heat energy is used to change an appropriate material property of the detector.
Information relevant to this invention can also be found in United States Patent and Parent Publication U.S. Pat. Nos. 6,576,572, 6,643,025, 6,753,969, 20040130728, 20060138347, and 20060181712 issued to Degertekin, et al.; each of the foregoing in United States Patent and Patent Publication Nos. is hereby incorporated herein by reference.
Each one of the above descriptions or references, however, suffers from disadvantages including; for example, one or more of the following, the invention is not directed at thermal detectors, or if directed at thermal detectors, the thermal detector has poor sensitivity, poor response time and noise. Other disadvantages of known thermal detectors include that they are not easily scalable and that they do not integrate a diffraction grating into each detector pixel to be combined with an optical readout to decrease the noise and improve the sensitivity.